INPP4A (inositol polyphosphate-4-phosphatase type I A) is a lipid phosphatase that hydrolyzes phosphatidylinositol 3,4-bisphosphate to generate phosphatidylinositol-3-phosphate 1. The enzyme localizes to multiple cellular compartments including the cytoplasm, nucleus, and perinuclear clusters associated with the endosomal marker Rab5, with subcellular distribution varying by INPP4A isoform 2. Mechanistically, INPP4A negatively regulates the PI3K/Akt signaling pathway 3 and can form a functional complex with cytochrome c to suppress ferroptosis by preventing lipid peroxidation 1. Biallelic INPP4A variants cause a spectrum of neurodevelopmental disorders ranging from moderate intellectual disability to severe presentations featuring postnatal microcephaly, developmental delay, myoclonic seizures, and (ponto)cerebellar hypoplasia 42. Disease severity correlates with variant location; mutations downstream of exon 4 produce more severe phenotypes, while upstream variants may permit translational reinitiation generating N-terminally truncated proteins with partial function 4. Beyond neurodevelopment, INPP4A dysregulation contributes to allergic and inflammatory diseases: deficiency promotes M2 macrophage polarization in eosinophilic chr2 rhinosinusitis 5, while reduced extracellular INPP4A associates with asthma pathogenesis 3. INPP4A represents an important regulator of cell proliferation, apoptosis, and endosomal trafficking with therapeutic potential across multiple disease contexts.